Studies in pteridophytes - IV. The development structure and organization of root in Isoetes coromandelina L.

This paper describes the structure arrangement, development of root and the organization of its apex in I. coromandelina and some other species. Though nothing strikingly different from what has already been described by Campbell (1891) about the organization of root apex has been found, it has nevertheless become clear from the structure arrangement and division figures of the cells of root apex that root promeristem can be distinguished in two regions-a central cylinder or 'core' upon which the inverted cup-shaped meristem or 'mantle' is present. A few meristematic cells of the 'core' give rise to the stele, while the cup-shaped meristem forms the whole cortex, the outer epidermis, the columella and the side tissues of root-cap. Orientation of division figures are considered as the main evidence for zonation. The branching is dichotomous. Roots are traversed by a monarch single eccentric stele. Around the vascular bundle the cortex disorganize and forms a "C"-shaped cavity-a characteristic feature of some of the fossil lycopods root. As regards the arrangement of roots present study of I. coromandelina confirms the early observations on I. japonica (West and Takeda, 1915). © 1963 Indian Academy of Sciences.